1. Technical Field
The present invention relates to a charged particle beam lens apparatus, a charged particle beam column, and a charged particle beam exposure apparatus.
2. Related Art
In the conventional art, complementary lithography is known according to which line patterns are formed by photolithography techniques and then processed using charged particle beams such as electron beams (see, for example, Japanese Patent Application Publication No. 2013-16744). In addition, it is known that a charged particle beam exposure apparatuses includes a plurality of charged particle beam columns arranged next to each other, each including charged particle beam lenses (see, for example, Proc. SPIE 7637, Alternative Lithographic Technologies II, 76370C (Mar. 10, 2010)). Also, it is known that charged particle beam lenses include heat eliminating units (see, for example, Japanese Patent Application Publications Nos. 61-227356 and 2014-120545).
Since such an exposure apparatus has a plurality of charged particle beam columns arranged therein, the lens sizes are limited. It is thus difficult for such an exposure apparatus to achieve high resolution while keeping the beam current value. High resolution can be accomplished by increasing the excitation current for the charged particle beam lenses to strongly excite the lenses. This, however, increases the heat generated by the charged particle beam lenses. To deal with the generated heat, the charged particle beam lenses may be provided with heat eliminating mechanisms and the like. This disadvantageously increases the sizes of the charged particle beam lenses. Considering the above, small charged particle beam lenses with high resolution are demanded.
For example, the following heat eliminating units have been proposed for the charged particle beam lenses. Firstly, double-layered components are introduced and cooling liquids are fed into the gap between the layers (see, for example, Japanese Patent Application Publication No. 61-227356). Secondly, a container having an excitation unit sealed therein is prepared and a cooling liquid is circulated in the container (see, for example, Japanese Patent Application Publication No. 2014-120545). These approaches, however, require addition of the new components to the charged particle beam lenses to form the cooling liquid flow channels. Thus, the charged particle beam lenses grow in size by the widths of the added components.